Changing fontstyle and size for headline rotator for responsive view

Hi,

i would like to adjust the headline rotator font-size and font-style on my startpage for all devices and mobile devices.

For all devices it should be:
line-height: 68px;
text-shadow: 1px 1px 5px #000000;
font-family: Arial, Helvetica, sans-serif;

devices max width 768px
font-size: 102px;
line-height: 102px;

devices max width 568px
font-size: 100%;
line-height: 90px;

devices max width 320px
font-size: 83%;
line-height: 66px;

What is the code for that and where do i need to add a code for that?

kind regards Jak